Effect of Soil Composition and Mulch on Ecohydrology of Aridland Rain Basins
Angela Knerl 1, Nathan Allen 2, Mitchell Pavao-Zuckerman 2
1 School of Natural Resources and the Environment, 2 Biosphere 2
University of Arizona
To maximize the use of scarce water supplies, arid cities could channel and capture stormwater runoff to increase water supply for urban populations. One approach to rainwater retention is the rain basin; a shallow, soil-filled hole that intercepts and absorbs water with natural features like soil and vegetation. Current basin design and implementation is mostly limited to temperate environments. We are initiating a study that aims to optimize soil and mulch basin composition to best intercept stormwater runoff in arid environments. We hypothesize that porous soil and bark mulch will (1) best intercept and retain stormwater and (2) increase ecological function (i.e. plant and microbial growth) given the full distribution of rain events in the Sonoran desert. We will test these hypotheses by installing 12 rain basins at Biosphere 2. Each basin will be filled with a soil (bottom) and mulch (top) combination; soils will consist of either soil from the site or a soil mixture. Surface mulches will consist of either rocks or bark. We will plant aridland-adapted shrubs in each rain basin to imitate common landscaping. During the monsoon season, we will measure rainfall, soil moisture, plant health, and microbial activity of each rain basin. Here, we present our experimental design and conceptual framework for this study. These experiments will improve aridland rain basin design by testing design parameters related to water retention and plant growth in a semi-arid climate. Ultimately, the more rain urban environments capture, the greater the water supply for growing aridland populations.